It is known that knowledge of the ridge lines of the relief of a particular geographical area is, in particular, very useful for rapid understanding of the limits of the inter-visibility areas in relation to an observation point on the ground, in flight or under water.
These data make it possible in particular for military personnel or mobile law enforcement agencies to know the progression spaces in which they can remain hidden from a potential enemy situated beyond.
Such ridge lines may, in particular, be used by mobile ground, air or submarine elements with automatic adaptation of the extraction of the ridge lines according to the altitude and the current position of these mobile elements.
This concept of ridge lines (in relation to a variable-height area) can also be used by analogy in the medical field, in particular in the study of the cerebral cortex, for which pseudo ridge lines of the brain can be considered to serve as starting points for defining functional areas.
To determine such ridge lines, a method implementing an extraction by analysis of the curvatures of a triangulated area is known.
However, this conventional method requires the availability of a triangulated area, and this makes it necessary to pre-process the altimetric data (available in matrix form or in raster form).
This conventional method is thus unsatisfactory.
Furthermore, a method and a device for automatically determining the contour of valleys of a geographical area are known from EP 0 863 487.